A seal section for location between a submersible rotary pump and motor has a primary mechanical seal and a secondary oil seal at the pump end of the seal section. The mechanical seal has rigid seal faces that slide in engagement with each other. The secondary seal has an inner portion that seals against the shaft of the seal section and an outer portion that seals against the housing. The seal section has a pressure equalizing device for equalizing pressure of motor lubricant with well bore pressure.