Caveling Spearmen are about as fast as a player without any speed increases, meaning it is quite hard to try and evade one, if necessary to. Avoiding one can be made easier by using a Swift Feather.
A Slingshot is a fairly effective weapon against Caveling Spearmen, allowing you to keep at a distance from one while still dealing a fair amount of damage.
Caveling Spearmen have a chance of dropping a Hunting Spear upon death, which is an extremely useful weapon against most enemies found in the Clay Caves, including the Spearmen themselves.
You can reduce Caveling Spearmen spawns by removing any Clay Moss that you come across, making it easier to traverse the Clay Caves.