Justin Bieber, Ariana Grande Remember Drummer Aaron Spears After Sudden Death

Justin Bieber and Ariana Grande are paying tribute to late drummer Aaron Spears after his sudden passing ... and it's clear Aaron left a lasting impression.

Both Justin and Ariana worked with Aaron -- a Grammy-nominated musician who also worked with Usher -- and Justin says, "We lost a beautiful man and inspiration to all of us drummers."

Justin's social media tribute includes a video of himself and another drummer jamming at WeHo's Peppermint Club, where JB and Hailey Bieber went to a Halloween party.

They were playing Usher's hit, "Bad Girl" from his blockbuster "Confessions" album ... on which Aaron played drums.

Aaron's wife announced his death Monday, and Ariana was quick to comment on the post ... and leave a similar response on her IG story.

Ariana says ... "I can't wrap my head around this. We were all so incredibly lucky to know Aaron. The absolute brightest light of a human being. Always the kindest, always smiling, I am so honored and thankful our paths crossed and to have spent so much very special time together."

Aaron's family hasn't announced a cause of death.

Ariana's post makes it clear how much he meant to those who knew him and worked with him -- "Thank you for your utter brilliance, for our laughs, and for your kindness always. I will miss your hugs. You are so, so loved and will be so very missed."

Aaron was 47.