Abstract: A pump, including a pump housing, defining an impeller chamber in fluid communication with a pump inlet and pump outlet. An impeller is rotatable within the impeller chamber and is attached to an adaptor shaft. The adaptor shaft is rotatably held in an intermediate housing that also serves as a mount for a drive source, such as an electric drive motor. A bearing held within the intermediate housing supports the adaptor shaft in both radial and axial directions and includes socket structure directly engageable with an output shaft of the drive motor. The socket structure includes clamping sections that are urged into frictional engagement with the output shaft of the drive source by a clamping device. The socket structure may include one or more slots for receiving a key carried by the drive shaft in order to provide a positive mechanical coupling between the drive source and the drive shaft.