a structural improvement of the canned pump is to improve the stiffness of a stationary shaft and , according to requirement , to dispose a monitor device . the method for improving the stiffness of the stationary shaft includes axially inserting a shaft metal rear support of the metal structural of a motor rear casing of a canned motor into the inner side of a rotor yoke of an inner rotor of the canned motor , tightly attaching the shaft metal rear support to a rear shaft seat for improving the stiffness of the stationary shaft by longer hold length , and for shortening an arm length of the composite force . the monitor device , used for detecting the wear of a bearing for enhancing the reliability and satisfying the driving requirement , is installed in the ring slot to be protected by the rear shaft seat .