Abstract: An improved immersible magnetically-coupled mixer has a plurality of rollable bearing assemblies readily cleanable by flushing in place and easily removable and replaceable without damage to either the mixer impeller or the bearings. The rollable bearings are resistant to corrosion, capable of running without lubrication, and have low propensity for batch contamination through wear. The rolling and fixed elements of the bearings are impervious to attack by the process materials being mixed, the rollable elements, preferably balls, can be formed of a hybrid ceramic such as silicon nitride, and the races can be formed of a nickel-beryllium or cobalt-chromium-tungsten alloy.