Bulk add new categories to Woo:
Insert category id, name, url key
INSERT INTO wp_terms
VALUES
(57, 'Apples', 'fruit-apples', '0'),
(58, 'Bananas', 'fruit-bananas', '0');
Set the term values as catergories
INSERT INTO wp_term_taxonomy
VALUES
(57, 57, 'product_cat', '', 17, 0),
(58, 58, 'product_cat', '', 17, 0)
17 - is parent category, if there is one
key here is to make sure the wp_term_taxonomy table term_taxonomy_id, term_id are equal to wp_term table's term_id
After doing the steps above go to wordpress admin and save any existing category. This will update the DB to include your bulk added categories