Housing removed exposing outer bearing. Inner and outer bearings are nearly back-to-back. This design is prone to damage due to leverage created by the tire and wheel assembly. Leverage is greatly increased with the use of larger than stock tires or wheels with less back spacing.
Inner bearing- note the plastic bearing cage. Excessive heat can cause cage distortion leading to complete bearing failure.
Like the inner bearing, the outer bearing also has a plastic bearing cage and is also prone to cause complete bearing failure when exposed to excessive heat.