A centrifugal pump assembly and method of using same including a vertical or horizontal overhung housing assembly having a primary inlet, a primary discharge, a secondary inlet and a secondary discharge. A shaft is in spaced relationship within the overhung housing assembly. A single primary impeller is mounted on the shaft for receiving fluid from the primary inlet and discharging fluid through the primary discharge. A booster impeller is mounted on the shaft and juxtaposed the main impeller for receiving fluid from the secondary inlet and discharging fluid through the secondary discharge. All fluid introduced to the secondary inlet originates from the primary discharge or may be diverted from the fluid flow upstream of the centrifugal pump assembly or the primary impeller. The fluid in the secondary inlet flows through the booster impeller and discharges through the secondary discharge. The secondary discharge is separate from the primary discharge.