Yes they CAN but is not a guarantee that they will regenerate. Most of a worm's organs are found from the mouth to the clitellum (collar or thick band).
They will not regrow but will most likely die if cut anywhere between those to body parts. This is also where the five hearts and brain is located.
If they're cut from behind (and well behind) the clitellum to the posterior end then there is a good chance they will regenerate.