An electrical submersible pump assembly has a motor cooperatively engaged with a pump for driving the pump and a motor lead extending to the motor for supplying power to the motor. The motor lead has an electrical conductor enclosed within a tube. The tube is sealed from an exterior environment of the motor and contains a dielectric fluid. The motor may be filled with a dielectric lubricant and the interior of the tube of the motor lead may be in fluid communication with the dielectric lubricant. Alternatively, the motor may filled with a dielectric lubricant and the dielectric fluid within the interior of the tube of the motor lead may be sealed from the dielectric lubricant.