Aspects of the disclosure can relate to an apparatus including a first member having a first bearing surface formed from a hard material (e.g., a diamond-based material, such as a polycrystalline diamond material), and a second member coupled to an input shaft to translate (e.g., rotate, slide, etc.) with respect to the first member. The second member has a second bearing surface formed from a hard material, and the second bearing surface is to bear against the first bearing surface. In embodiments of the disclosure, the first and second members can be for devices including, but not necessarily limited to: solenoids, generators and/or motors (e.g., out-runner radial flux generators, axial flux generators, radial flux generators/motors, roller vane motors, etc.), gearboxes, rotary data swivels, digital actuators, filters (e.g., inner rotating filters), valves (e.g., proportional valves), sensors (e.g., pressure differential sensors), and so forth.