A power cable assembly supplies power to and suspends in a well an electrical well pump. The assembly includes metal tubing having a longitudinal tubing center line and a cylindrical side wall. Power cable has an exterior delta shape when viewed in a cross-section. The delta shape defines three exterior side surfaces that face radially outward and join each other at corners. Power cable has three insulated power conductors wrapped helically with a metal strip. The power cable is located in the tubing with the corners deformed against an inner diameter of the tubing.