Any brushed motor will wear out if run continuously even if its loaded lightly. Even if windings are intact, if not the brushes then the commutators will wear - faster or slower depends on the thickness or materials used.
UPDATE: (some words were corrupted)
This statement is NOT valid for many motors. Our brush type fuel pump motor is rated to last 15 years or more at automotive usage rates. the difference is we pass the fuel through the motor to keep the windings cool.