A method of joining parts, where at least one of the parts has a faying surface defining grooves therein. One of the parts is formed of a majority of titanium, and the other part is formed of a majority of iron. The method includes providing a set of opposed welding electrodes disposed on a side of each part and applying pressure to and heating the parts via the set of electrodes to form a joint between the parts. A bonded assembly includes a first part formed of a majority of titanium and a second part formed of a steel alloy. The first and second parts having a bond that includes a portion of the first part directly in contact with and attached to a portion of the second part. The parts may be a titanium-containing differential carrier case bonded to a steel gear.