A downhole tool comprises a plurality of blades that extend outward from a tool body. Each blade has an under-gauge surface with a blade diameter that is less than a gauge diameter of a drill bit to be used with the downhole tool. A waterway is defined between a pair of adjacent blades and has a waterway base that is recessed from the blade diameter. One or more waterway inserts are disposed within the waterway and extend from the waterway base. Each of the one or more waterway inserts does not extend to the blade diameter. No component of the downhole tool is positioned outside the blade diameter.
