referring to fig1 , an electric pump assembly of the present invention is designated in its entirety by the reference number 20 . the assembly 20 includes an electric motor , generally designated by 22 , and a centrifugal pump , generally designated by 24 . as illustrated in fig2 , the electric motor 22 includes a generally cylindrical case 26 , a front endshield 28 at one end of the case , a back endshield 30 at an end of the case opposite the front endshield , and a selectively rotatable drive shaft 32 projecting through the front endshield . in the illustrated embodiment , the electric motor includes a bracket 34 for attaching the motor 22 to a support on a larger apparatus such as a spa tub . as will be appreciated by those skilled in the art , the drive shaft 32 rotates about its imaginary longitudinal axis when electricity is supplied to the motor 22 . a shoulder 36 is provided on the front endshield 28 of the motor 22 for centering the pump 24 on the shaft 32 . because the electric motor 22 is conventional , it will not be described in further detail . as shown in fig2 and 3 , the centrifugal pump 24 includes a primary enclosure or housing 38 having a threaded inlet port 40 and a threaded outlet port 42 , each of which is adapted to be attached to conduits ( not shown ) for transporting fluid to and from the pump . the enclosure 38 houses an impeller 44 that is operatively connected to the drive shaft 32 of the motor 22 . in one embodiment , the impeller 44 is connected to the drive shaft 32 by a coupling 46 so the impeller turns with the drive shaft . as the impeller 44 turns , it draws fluid into the pump 24 through the inlet port 40 and expels fluid out of the pump through the outlet port 42 . as further illustrated in fig2 , the pump 24 includes a mounting structure , generally indicated at 50 , having a volute body 52 surrounding by a flange 54 . in one embodiment , the mounting structure 50 is molded as a single piece of polymeric material but may be formed as several pieces and joined together . for example , the volute body 52 may be formed separately from the flange 54 and assembled to the flange with fasteners or adhesive . although the pump 24 is illustrated as being a centrifugal pump , those skilled in the art will appreciate that the pump may be another type without departing from the scope of the present invention . moreover , those skilled in the art will appreciate that the principles of the present invention may be applied to motors attached to devices other than pumps . as shown in fig3 , the flange 54 of the mounting structure 50 is generally circular . further , the mounting structure 50 includes a central opening 56 allowing the drive shaft 32 of the motor 22 to pass through the mounting structure to the pump impeller 44 . the mounting structure 50 also includes a plurality of connector bosses or elements 58 spaced angularly around the central opening 56 for connecting the flange to the motor 22 . the connector elements 58 are joined by an annular wall 60 and supported by radial ribs 62 . one or more of these ribs 62 may include a notch 64 for engaging the shoulder 36 on the motor 22 front endshield 28 to center the mounting structure 50 on the motor . in one embodiment , each connector element 58 has a generally racetrack - shaped cross section and projects axially outward from the mounting structure 50 in a direction opposite the volute body 52 . referring to fig4 , the connector elements 58 are each adapted to receive an insert 66 made of a material having sufficient strength to resist damage from fastener loading . although the insert 66 may be made from other materials without departing from the scope of the present invention , in one embodiment each insert is made of brass suitable for retaining a fastener 68 . for example , in one particular embodiment the fastener 68 received by the insert 66 is a threaded bolt or stud as shown in fig5 . further , in one embodiment the insert 66 includes a rough ( e . g ., knurled or fluted ) exterior to improve interface shear strength with the connector elements 58 . inserts 66 having other configurations ( not shown ) may be used without departing from the scope of the present invention . more particularly , the connector elements 58 are formed with cylindrical cavities 70 sized to receive the threaded inserts 66 and retain them in the cavities . for example , in one embodiment the cavities 70 are sized to have an interference fit with the inserts 66 so the inserts may be pressed into place . in another embodiment , the inserts 66 are molded into the connector elements 58 . in still another embodiment , it is envisioned that the inserts 66 may be adhesively bonded in position . as illustrated in fig6 , each connector element 58 has a void 72 to reduce the amount of material needed to form the connector element . as further shown in fig7 and 8 , the voids 72 are shaped on their sides adjacent the cavities 70 so that the walls separating the voids and the corresponding cavities have a generally constant thickness . thus , the voids 72 have an overall crescent - shaped cross section . other configurations of cavities and voids may be used without departing from the scope of the present invention . in one embodiment , the voids 72 could be omitted entirely . different motors 24 may have different fastener positions . the shape of the connector elements 58 permits the mounting structure 50 to be easily molded in more than one configuration for mounting the same centrifugal pump 24 to different motors 22 having different fastener positions . for example , the motors 22 may have different fastener diameters , different radial fastener positions or different circumferential fastener spacing , but the pump itself would have a similar internal configuration . in a second embodiment illustrated in fig1 , the connector elements 58 ′ could be arranged to connect to different motors 22 having similar circumferential fastener spacing but different radial fastener positions . the cavities 70 ′ for receiving the threaded inserts 66 ′ can be disposed on the radially outer ends , and the voids 72 ′ on the radially inner ends of the connector elements 58 ′. the construction of the mounting structure 50 ′ of fig1 is identical to the mounting structure 58 of fig6 - 8 , except for the location of the cavities 70 ′ and the voids 72 ′, which are reversed from the location of the cavities 70 and voids 72 of the first embodiment . the parts of the mounting structure 50 ′ of fig1 will be given the same reference numerals as the mounting structure 50 , but with the addition of a trailing prime (′). the mounting structure 50 ′ is constructed for receiving mounting bolts ( not shown ) located radially farther outward than the bolts 66 that are received by the mounting structure 50 of fig6 - 8 . moreover , the threaded inserts 66 ′ have a different inner diameter for receiving a different diameter fastener . the outside diameter of the threaded inserts 66 ′ is the same as that of the threaded inserts 66 of the first embodiment so the same size cavities 70 ′ are used in both embodiments . the mounting structures 50 , 50 ′ having different threaded insert cavity 70 , 70 ′ and void 72 , 72 ′ positions can be formed in the same mold , generally designated 80 in fig1 - 13 . the mold 80 includes a first mold member 82 and a second mold member 84 that are joined and separated as known to those of ordinary skill in the art . the first mold member 82 is formed to shape the volute 50 , 50 ′ and the second member 84 is formed to create the opposite side of the mounting structure 50 , 50 ′ including the connector elements 58 , 58 ′. the second mold member includes sub - inserts 86 that can be used to form both the connector elements 58 of fig1 - 7 and the connector elements 58 ′ of fig8 . the sub - inserts 86 comprise a stepped base 88 , a cavity core 90 and a void core 92 . the cavity core 90 and void core 92 both project from the base . the cavity core 90 has a generally cylindrical shape , and the void core 92 has a roughly crescent shape , corresponding to the shape of the cavity 68 , 68 ′ and void 70 , 70 ′, respectively . each sub - insert 86 is releasably mountable on the second mold member 84 so that the sub - insert can be removed through the back of the second mold member as shown in fig1 . it is envisioned that the cores 90 , 92 may be replaced with other cores ( not shown ) having different configurations . the base 88 is generally rectangular in shape with rounded corners , and is received in a correspondingly rectangular aperture 94 in the second mold member 84 . it will be appreciated that the base 88 can be received in one of two positions in the aperture 94 of the second mold member . in a first of these positions illustrated in fig1 , the sub - insert 86 is arranged so that the cavity core 90 is located radially inward from the void core 92 for forming the mounting structure 50 as shown in fig8 . in the second position illustrated in fig1 , the sub - insert is arranged so that the cavity core 90 is located radially outward from the void core 92 for forming the mounting structure 50 ′ as shown in fig1 . thus , it may be seen that by simply detaching the sub - insert 86 , rotating it and reinserting the sub - insert into the second mold member 84 , the second mold member can be converted to selectively produce either the mounting structure 50 of the first embodiment or the mounting structure 50 ′ of the second embodiment . no separate sub - insert is required . the previously described shoulder 36 and notched ribs 62 engage each other to align the shaft 32 of the motor 22 with the pump 24 . these features prevent the shaft 32 and pump 24 from becoming misaligned which can damage seals in the pump . these features are particularly advantageous when the electric pump assembly 20 is jarred during transport . when introducing elements of the present invention or the preferred embodiments ( s ) thereof , the articles “ a ”, “ an ”, “ the ” and “ said ” are intended to mean that there are one or more of the elements . the terms “ comprising ”, “ including ” and “ having ” are intended to be inclusive and mean that there may be additional elements other than the listed elements . in view of the above , it will be seen that several advantages are achieved by the present invention . as various changes could be made in the above constructions , products , and methods without departing from the scope of the invention , it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense .