a shear coupling assembly utilizes a second coupling member , a first coupling member and a locking member which is inserted into a bore in the first coupling member to connect between the second coupling member and the first coupling member . in embodiments where a pretension is applied to the shear neck , the locking member maintains the pretension in the shear neck . the bore of the first coupling member has a profiled section which corresponds to a profiled section on the second coupling member which when mated together permit torque to be transferred for co - rotating the second coupling member with the first coupling member for use in rotary pump operations . advantageously , the profiled portions and the shear neck are encased in the bore of the shear coupling assembly and are protected from corrosive wellbore fluids .