A well pump assembly has a rotary pump with an electrical motor that contains a motor lubricant. A thrust chamber is mounted between the motor and the pump, the thrust chamber containing a thrust chamber lubricant. Seals prevent the entry of thrust chamber lubricant into the motor chamber. A pressure equalizing chamber is mounted to the motor for admitting well fluid. A first pressure barrier in the equalizing chamber equalizes the pressure of the thrust chamber lubricant with that of the well fluid. A second pressure barrier contained within the first pressure barrier equalizes the pressure of the motor lubricant with thrust chamber lubricant.