Wheel Bearing Wear - Front Drive Axle (Tapered): Galling
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Galling
Courtesy of GENERAL MOTORS CORP.
Metal smears on the roller ends due to overheating, lubricant failure, or lubricant overload. Replace the bearing. Check the seals. Check for proper lubrication.