US Patent 7290984 Multistage pump

A centrifugal pump includes plural pump stages, each comprising an impeller assembly, a stationary disc assembly and a diffuser assembly, all disposed about an impeller shaft. A floating impeller hub seal is supported by a diffuser assembly to minimize fluid recirculation. A thrust washer is disposed around the impeller shaft and is engageable with an impeller hub and the hub seal. A wear ring is secured to a disc assembly and engageable with a wear surface on the impeller.