Abstract: A replaceable lining for a centrifugal pump casing includes a continuous substantially rigid shell made of thermoset plastic resin material reinforced with woven roving fiberglass fabric sheets and randomly dispersed glass fibers. The lining also includes an elastomer layer bonded to an inner surface of the rigid shell. Both the elastomer layer and the shell have a volute section and a semicylindrical or semiconical discharge section integral therewith. The discharge section of the shell is provided along an outer surface with a set of outwardly projecting arcuate reinforcement ribs spaced along the discharge section. The ribs are integral with the shell. The shell is preformed and adhesively bonded to the elastomer layer during a compression molding step of a manufacturing process.