Is insert a noun

Yes, the Word 'insert' is both a noun (insert, inserts) and a verb (insert, inserts, inserting, inserted).

The noun 'insert' is a Word for a loose page or section carrying an advertisement in a magazine or other publication; an ornamental section of cloth or needlework in the material of a garment; a shot incorporated into a movie or video; a Word for a thing.

The noun forms of the verb to insert are inserter, insertion, and the gerund, inserting.