A submersible pump assembly includes a seal section connected to a motor, the seal section having a housing with an outboard bearing at a housing pump end in radial supporting engagement with a drive shaft. An inboard bearing is also in the housing pump end, axially spaced from the outboard bearing, and in radial supporting engagement with the shaft. A barrier fluid chamber in the housing pump end contains a barrier fluid. A primary shaft seal is located within the barrier fluid chamber and seals the barrier fluid in the barrier fluid chamber from the motor lubricant. A secondary shaft seal is mounted in the barrier fluid chamber between the primary shaft seal and the outboard bearing. The secondary shaft seal seals the barrier fluid in the barrier fluid chamber from well fluid exterior of the housing pump end.