我想出来了。我创建了一个插件，为random_password, 像这样：

function my_password_filter($input) {

    $words = explode(\' \', "apple arm banana bike bird book chin clam class clover club corn crayon crow crown crowd crib desk dime dirt dress fang field flag flower fog game heat hill home horn hose joke juice kite lake maid mask mice milk mint meal meat moon mother morning name nest nose pear pen pencil plant rain river road rock room rose seed shape shoe shop show sink snail snake snow soda sofa star step stew stove straw string summer swing table tank team tent test toes tree vest water wing winter woman women");

    $num = rand(100, 999);

    return $words[array_rand($words)] . $num . $words[array_rand($words)];

}

add_filter(\'random_password\', \'my_password_filter\', 10, 1);