Adam Clarke on Numbers 13:16

And Moses called Oshea Jehoshua - Oshea, Heb. הושע should be written Hoshea: the word signifies saved, or a savior, or salvation; but יהושע, he shall save, or the salvation of God; a letter, says Calmet, of the incommunicable name of God, being added to his former name. This was not the first time in which he had the name Joshua; see Exo 17:9 (note), and the note there. Some suppose he had this change of name in consequence of his victory over Amalek; see Exo 17:13, Exo 17:14.