Как объединить два массива по значению ключа?

<?php

$users = [
    [
        "userUuid"   => "032b83b4-3ad8-33fd-abd3-bfafc5eb23ba",
        "name"       => "Илья",
    ],
    [
        "userUuid"   => "59281d2d-d81e-3556-956b-f354fd5e24a9",
        "name"       => "Олег",
    ],
];
$resources = [
    ['user_id' => '59281d2d-d81e-3556-956b-f354fd5e24a9', 'processed' => 145, 'assigned' => 167],
    ['user_id' => 'e9f60f90-3096-3848-b3e6-094e81f9b022', 'processed' => 15, 'assigned' => 177],
];

$result = array_map(function($user) use ($resources) {
    $second = array_filter($resources, function($resource) use ($user) {
        return $resource['user_id'] === $user['userUuid'];
    });
    return array_merge(
        $user,
        count($second) ? $second[0]: []
    );
}, $users);

var_dump($result);

$result = array_map(function($user) use ($resources) {
    return array_merge(
        $user,
        ...array_filter($resources, fn($resource) => $resource['user_id'] === $user['userUuid'])
    );
}, $users);

var_dump($result);

$result = array_map(fn($u) => array_merge($u, ...array_filter($resources, fn($r) => $r['user_id'] === $u['userUuid'])), $users);

var_dump($result);