The system and method of the invention pertains to use of a back iron on one or both ends of the impeller to increase the magnetic field density, and thus strengthen the magnetic coupling. In addition, pie-shaped (i.e. wedge) magnets, or variations thereof, increase the utilization volume and hence provide higher torque to allow the use of less expensive material (e.g. ferrites). In another embodiment, the rotor side is constructed with a Halbach array which increases the torque without the need to add a back iron piece. In another embodiment, an axial flux stator is implemented to replace the drive-end magnets and the drive motor.