If you are programming games in Python it might be interesting to have a look at PyGame: http://www.pygame.org/
What you are looking for is the concept of 'Path finding'.
More technically, you might have a look into 'vector' usage (either 2D or 3D).
LocationCurrentSprite = Vector(...)
LocationNPCSprite = Vector(...)
distance = function of vectors
direction = function of vectors