A torque transfer assembly comprising a drive shaft and a driven shaft and a dielectric insert arranged to be positioned between the drive shaft and the driven shaft, the insert assembly comprising a body of dielectric material shaped to form an insulating layer and configured to engage, respectively, with a first shaped engagement feature on the drive shaft and a second shaped engagement feature on the driven shaft, in torque transfer engagement, the insulating layer providing a dielectric barrier between the drive shaft and the driven shaft.