The wheel bearings that are fitted to both wheels are not sealed on both sides. So power washing the wheels is not such a good idea. Picture below shows wheel bearings as factory fitted.
Picture below shows new double sided seal bearings. Use only branded high quality bearings from a reliable source such as Simply Bearings. Rear wheel bearings are type 6204 and front bearings are 6203,oil seals are also available from this company.
To remove the old bearings a slide hammer is needed and a heat gun. The slide hammer is available from around £15 on that well known auction website, likewise the heat gun. Pictures shown below.