A centrifugal water pump for use in a diesel engine cooling system provides an improved water pump construction including multiple features which combine to provide increased operating life for the supporting and wearing components of the pump. The improvements include one or more of: a water seal system is provided having a stationary seal and a rotating seal made of silicon carbide with at least one of the seals having embedded lubricant; an o-ring added to the stationary seal ensures that pressurized water does not get past the stationary seal; metallic bearing seals and covers to prevent leeching of the lubricant from the bearing; optimized spring force on the rotating seal; tapered shaft impeller interface to minimize torsional stresses on these components from the keyway design of the prior art; and the housing engine oil inlet is removed to prevent the direct flow of hot, dirty, and contaminated oil from damaging the water pump bearings.