A submersible well pump assembly for pumping well fluid, comprising: a pump; a motor that drives the pump, the motor being filled with a motor lubricant; a housing having a longitudinal housing axis and operatively mounted to the motor; an expandable and contractible pressure equalizer within the housing, defining a pressure equalizing chamber in the housing that surrounds an exterior of the pressure equalizer; a motor lubricant communication path (49, 51) for communicating motor lubricant from the motor to an interior of the pressure equalizer; a well fluid inlet port in the housing for admitting well fluid into the pressure equalizing chamber; a check valve passage leading from the motor lubricant communication path to the pressure equalizing chamber; a check valve in the check valve passage configured to expel motor lubricant from the motor lubricant communication path into the pressure equalizing chamber when the pressure of the motor lubricant in the interior of the pressure equalizer is at a selected level above the pressure of the well fluid in the pressure equalizing chamber; a dip tube having a dip tube inlet at the check valve passage and extending from the check valve passage into the pressure equalizing chamber, the dip tube having a dip tube outlet that, when the dip tube is in a mounted state, lies at a lower elevation relative to the housing axis than the dip tube inlet; and wherein: the check valve is at a higher elevation relative to the housing axis than the dip tube inlet; and characterized in that: the dip tube has at least one crest and at least one valley between the dip tube inlet and the dip tube outlet, the crest being at a higher elevation relative to the housing axis than the valley when the dip tube is in the mounted state. a pump; a motor that drives the pump, the motor being filled with a motor lubricant; a housing having a longitudinal housing axis and operatively mounted to the motor; an expandable and contractible pressure equalizer within the housing, defining a pressure equalizing chamber in the housing that surrounds an exterior of the pressure equalizer; a motor lubricant communication path (49, 51) for communicating motor lubricant from the motor to an interior of the pressure equalizer; a well fluid inlet port in the housing for admitting well fluid into the pressure equalizing chamber; a check valve passage leading from the motor lubricant communication path to the pressure equalizing chamber; a check valve in the check valve passage configured to expel motor lubricant from the motor lubricant communication path into the pressure equalizing chamber when the pressure of the motor lubricant in the interior of the pressure equalizer is at a selected level above the pressure of the well fluid in the pressure equalizing chamber; a dip tube having a dip tube inlet at the check valve passage and extending from the check valve passage into the pressure equalizing chamber, the dip tube having a dip tube outlet that, when the dip tube is in a mounted state, lies at a lower elevation relative to the housing axis than the dip tube inlet; and wherein: the check valve is at a higher elevation relative to the housing axis than the dip tube inlet; and characterized in that: the dip tube has at least one crest and at least one valley between the dip tube inlet and the dip tube outlet, the crest being at a higher elevation relative to the housing axis than the valley when the dip tube is in the mounted state.