A high-efficiency, multi-stage centrifugal pump and method of assembly. The pump can include three pump stages with each one of the three pump stages including a front casing, a back casing, an impeller, and a bladed diffuser. The front casing and the back casing are removeably coupled around the impeller and the bladed diffuser. In the three-stage pump, the fluid can be pumped at a flow rate between about 300 liters per second and about 500 liters per second with an efficiency between about 86% and about 91%. The method includes separately casting, machining, and polishing each one of the front casing, the back casing, the impeller, and the bladed diffuser.