A seal cartridge (28) for a centrifugal pump (20) includes a housing (30) that fits within a conventional stuffing box of the pump and has a cylindrical internal surface receiving the shaft (26). A pair of annular grooves (34, 36) are provided internally of the housing adjacent respectively opposite ends thereof. Each groove receives an O-ring that runs in contact with the sleeve when the shaft rotates. The sleeve (40), housing and O-rings (38) define an annular chamber through which water is circulated to cool and lubricate the O-rings. The water is pressurized to cause the O-rings to deform and seal against the sleeve.