A bearing and seal assembly for supporting and sealing a terminating outboard end of an impeller shaft in a centrifugal pump such as a between-bearings pump includes only one seal but provides advantages typical of a dual-seal assembly, including barrier fluid protection against seal damage caused by abrasive slurries, and protection against leaking of toxic process fluid to atmosphere. A bearing housing sealed to the pump's pressure casing encloses the seal, bearing, and terminating impeller shaft end. Leakage of process fluid past the seal is prevented by a lubricating, pressurized, cooled barrier fluid which is circulated through the bearing housing by an external pump and/or by an internal, shaft-driven impeller. Because the impeller shaft terminates within the bearing housing and does not penetrate to atmosphere, the barrier fluid is contained within the bearing housing and a second seal is not required.