Martin Odegaard and an own goal saw the Gunners return to the top of the table.
"Very happy," said Arteta. "It was a really difficult game and credit to Luton, they are a very good side and make it difficult for us.
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"We scored two really good goals in the first half, in the second half because of the way they play we didn't get the right rhythm.
"I am so happy with the boys who came in, they made a difference. Now we have a bigger squad with nearly everyone fit and available."
On Emile Smith Rowe, he added: "I was really impressed with him. He has been training really well and we felt the game could suit us.
"Really pleased for the boys who came in.
"It is a busy month, we have started well again after an international break and next is Brighton."