a bus bar formed of a first electrically conductive material having a planar contact portion, wherein the bus bar defines a first bore extending through the contact portion; and

a contact insert formed of a second electrically conductive material that has a greater hardness than the first electrically conductive material, wherein the contact insert defines a first surface that is mechanically and electrically connected to the contact portion of the bus bar and wherein the contact insert defines a second surface plated with a third electrically conductive material different than the second electrically conductive material, wherein the contact insert defines a smooth second bore coaxial with the first bore and extending from the first surface to the second surface, wherein the contact insert defines a cylindrical collar extending from the second surface and defining an annular groove therein, wherein the collar includes a lip extending over the annular groove, and wherein the second surface defines a plurality of alternating projections and indentations radially extending beyond the lip and the collar.