Is it redundant to add umami to tomato-based sauces?
The Wikipedia article you link actually hints at an answer. It points out that there's a synergistic effect when combining different classes of umami-rich foods, leading to a greater flavour enhancement than would be expected simply by adding the effects of the ingredients 


  Japanese make dashi with kombu seaweed and dried bonito flakes;... and Italians combine Parmesan cheese on tomato sauce with mushrooms.


So it's certainly traditional. But in your example the tomatoes bring some sweetness along with the umami, while the Worcester sauce (like soy sauce) is salty and so rich in umami it's used in small quantities. The effect of combining them is a more savoury sauce than one that tried to get all its umami from tomatoes. Red pesto uses parmesan to similar effect.