A technique is provided for improving the efficiency of a centrifugal pump. The centrifugal pump comprises diffusers that optimize the area schedule through the diffuser to diffuse the total fluid velocity and recover dynamic head while minimizing flow separation. Each diffuser comprises an improved transition from the diffuser blade into the diffuser discharge duct to remove abrupt changes in area and to reduce fluid separation. The impellers also can be constructed with impeller transitions able to reduce fluid separation and improve the efficiency of the pump.