MakeArray.php

<?php
$arr_a = array('1','2','3','4','5','6');
$arr_b = array('apples','oranges','bananas','peaches'); 

function makeArray($array_a, $array_b) {
	$newArr = $array_a;

	foreach($array_b as $value)
	{
		$rand = rand(0, count($newArr) - 1);
		array_splice($newArr, $rand, 0, array($value));
	}
	
	return $newArr;
}

var_dump(makeArray($arr_a, $arr_b));